<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>css练习</title>
    <style>
        * {
            border: 1px purple solid;
        }
        #one {
            margin-bottom: 10px;
            padding-top: 40px;
            padding-bottom: 20px;
            padding-left: 10px;
            padding-right: 5px;
            width: 40px;
            height: 40px;
        }
        #two {
            margin-top: 20px;
            margin-bottom: 10px;
        }
        span {
            display: block;
        }
    </style>
</head>
<body>
    <div id="one">111</div>
    <div id="two">222</div>
    <div id="three"><span>333</span></div>
</body>
</html>